title: Facile synthesis and step by step enhancement of blue photoluminescence from Ag-doped ZnS quantum dots.
abstract: Our results pertaining to the step by step enhancement of photoluminescence (PL) intensity from ZnS:Ag,Al quantum dots (QDs) are presented. Initially, these QDs were synthesized using a simple co-precipitation technique involving a surfactant, polyvinylpyrrolidone (PVP), in de-ionised water. It was observed that the blue PL originated from ZnS:Ag,Al QDs was considerably weak and not suitable for any practical display application. Upon UV (365 nm) photolysis, the PL intensity augmented to ~170% and attained a saturation value after ~100 min of exposure. This is attributed to the photo-corrosion mechanism exerted by high-flux UV light on ZnS:Ag,Al QDs. Auxiliary enhancement of PL intensity to 250% has been evidenced by subjecting the QDs to high temperatures (200 °C) and pressures (~120 bars) in a sulphur-rich atmosphere, which is due to the improvement in crystallanity of ZnS QDs. The origin of the bright-blue PL has been discussed. The results were supported by X-ray phase analysis, high-resolution electron microscopy and compositional evaluation.
authors.affiliation: National Physical Laboratory, Council of Scientific and Industrial Research, Dr. K.S. Krishnan Road, New Delhi 110 012, India.
authors.forename: Sonal
authors.initials: S
authors.lastname: Sahai
authors.forename: Mushahid
authors.initials: M
authors.lastname: Husain
authors.forename: Virendra
authors.initials: V
authors.lastname: Shanker
authors.forename: Nahar
authors.initials: N
authors.lastname: Singh
authors.forename: D
authors.initials: D
authors.lastname: Haranath